Tetrazine-argon

Six symmetrically disubstituted derivatives of r-tetrazine have been studied by linear dichroism spectroscopy in the UV-Vis region, magnetic circular dichroism spectroscopy, and theoretical calculations of structures and spectra <1995CPH(200)201>. A detailed discussion of the sensitivity and of the optothermal detection scheme for the study of nonfluorescing excited states of the r-tetrazine-argon van der Waals complex has been presented <2000MI183>. 

It has been shown that the relaxation of vibrational levels of the tetrazine-argon complex is sequential (IVR prior to VP). It would be important to know whether such a behavior is characteristic for a large class of... 

Tetrazine-argon Tetrazine-krypton Tetrazine-xenon... 

TABLE VIII. SUMMARY OF THE EXPERIMENTAL DATA FOR THE SYSTEM Si TETRAZINE-ARGONS. 

Tetrazine-argon van der Waals complexes were produced by expanding s-tetrazine seeded in argon at a pressure of 1.2 bar through a 100 pm orifice into a vacuum chamber which was evacuated by two roots pumps (500... 

Studies of IVR and VP in molecular clusters available in the literature come from the laboratories of Levy,. 5 ito,6 Soep, Rice,8 Paramenter,9 Rettschnick,iO and Bernstein.il In most of these instances cw (pulse width greater than 5 ns) experiments are performed on the clusters and dynamical behavior is inferred from the dispersed emission. Some time resolved dynamical studies have recently appeared on tetrazine/argon,8.l0 p-difluorobenzene/argon, the dimethyltetrazine dimer,5.i2 and the benzene/phenol dimeri3 which will be briefly discussed below. 

The ground state data for tetrazine/argon,8c-photon resonant fluorescence technique, indicate that little or no rVR occurs on the 15 ns timescale for S . The ground state IVR relaxation times are in sharp contrast to the excited state times this difference has been explained in terms of different chromophore-vdW mode interactions in each electronic state. These authors postulate that the extent of vibrational coupling is indicated by the spectral bandshifts which occur upon clustering. 

We have performed detailed quantitative numerical simulations based on the above qualitative ideas. These simulations which closely follow those published by us for the tetrazine/argon system,2b generate quantitative predictions of the spectral quantum yields and the kinetic behavior of all observed features. The calculated and observed intensities agree quite well -within a factor of two. The calculated and observed kinetics are also in good agreement - again within a factor of two in nearly all instances. 

Amino-l,2,4,5-tetrazine - argon (1/1) (weakly bound complex)... 

The analogous reaction between benzocyclopropene and dimethyl l,2,4,5-tetrazine-3,6-di-carboxylate proceeded at room temperature under argon with loss of nitrogen to give dimethyl 4a,8a-methanophthalazine-l,4-dicarboxylate (6) in 97% yield. In contrast to the adducts of triazines, which have a heteroannulene structure, those of tetrazines occur as norcara-dienes. The methanophthalazine 6 underwent nucleophilic addition to the C-N double bond with a variety of mild nucleophiles. 

Van der Waals complexes were observed between two molecules of 1,2,4,5-tetrazine (la) and helium, argon, krypton, xenon, hydrogen, water, hydrochloric acid, acetylene or benzene 28 36- 396-420 jn coi,j environment of a jet expansion. In favorable systems it has been possible to determine the ground and excited state geometry of the cluster by laser spectroscopy. From these structures, it has been found that 1,2,4,5-tetrazine possesses a number of different binding sites. Helium and argon bind to the equivalent sites above and below the ring.28-30 The predominant interaction in these clusters is presumably the attractive dispersion force. 

We have studied the vibrational energy flow in photoexcited van der Waals complexes T Ar of s-tetrazine and argon. The aim of this paper is to present experimental information about the coupling among the van der Waals vibrational modes in T Ar and about the interaction between ring modes and vdW vibrations. 

Very few experiments providing direct information about the pathways of intramolecular energy flow in van der Waals complexes have been reported to date. In most cases studied so far, distinct channels for IVR and vibrational predissociation (VP) could not be detected separately. Among the polyatomic van der Waals complexes the cluster T Ar of s-tetrazine and argon is one of the few favourable exceptions. It exhibits several channels for... 

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